This invention relates to providing a shingle or shingle layer of increased thickness, whether the shingle layer comprises a single layer shingle, or a single layer of a multiple-layer shingle.
Shingles are generally made by providing a bitumen-coated web, with the web being either of organic or inorganic (generally fiberglass) material. The bitumen is generally asphalt. The front or top surface of the shingle or shingle layer is provided with granules, generally of a certain predetermined size, which granules are embedded in the asphalt or other bitumen that coats the web. The construction and arrangement of such granules can take on various forms, for various purposes, such as color, light reflection, fungus-resistance, ultra-violet or infrared reflectiveness, or of any other forms, for facilitating the longevity of the shingle, or simply for aesthetic purposes. Where aesthetics are important, the granules can be various combinations of colored granules, or various arrangements of color, all of which are known in the art.
The bottom or rear surface of the shingle is generally provided with a very thin layer of adhesive, such as asphalt or other bitumen coating. Fine particles are applied to this very thin layer of adhesive coating on the bottom, or rear surface of the shingle. Such fine particles can include sand, limestone, talc, mica, etc. embedded in the fine adhesive coating.
Attempts have been made to produce shingles having ordinary roofing granules embedded in this thin layer of adhesive coating on the rear surface of the shingle. However, if granules of an approximate size such as those that are used on the front or top surface of the shingle or shingle layer are used, to be embedded in the very thin layer of adhesive coating that is applied to the rear of the shingles, the adhesion provided by the thin layer of coating is not sufficient to ensure that the granules will remain embedded in the thin layer of adhesive coating, such that such granules on the rear surface of the shingle can become loose, creating safety issues on the roofing by acting like small roller bearings under the feet of the contractor or other installer, potentially causing slipping, sliding and accidents.